1. Enabling the Variable Power On Function
The NI-VXI driver allows the user to power on and off the VXI chassis after powering on the host workstation, without having to power cycle, by enabling the VXI Variable Power On Function (VPO). The VPO function can be enabled through NI Measurement & Automation Explorer (MAX).
The VPO function is not supported on systems that have PCI Express Native Control enabled. In order to use the VPO feature, the user will need to disable the PCI Express Native Control on the system with the following procedure:
- Open the Windows Command Prompt with administrative privileges. This can be done by searching Windows for 'cmd', right-clicking on the Command Prompt application, and selecting 'Run as Administrator'.
- Enter the following command: "bcdedit /set pciexpress forcedisable".
- Reboot the system.
2. Re-Enabling PCI Express Native Control
PCI Express Native Control can be re-enabled by an administrative user by entering the following command at the Command Prompt: "bcdedit /set pciexpress default".
3. Potential Challenges When Enabling the Variable Power On Function
In some cases enabling VPO can result in the system entering a state where Windows hangs during boot. If this occurs, the system can be restored through the following procedure:
- Power down the computer.
- Disconnect the MXI card from the PCIe slot on the computer's motherboard.
- Power the computer on. With the VXI hardware removed from the system, Windows should boot normally without hanging.
- Disable VPO through MAX.
- Power down the computer again.
- Reconnect the MXI card to the PCIe slot on the computer's motherboard and ensure all VXI hardware is connected normally.
- Power the computer on. With VPO disabled, Windows should boot normally without hanging.
4. Related Resources
- External: Microsoft: Enabling PCI Express Native Control in Windows
- KnowledgeBase 5RLEB371: MXI-Express Products that Support NI-VXI Variable Power On
- Drivers & Updates: NI-VXI
- Manuals: VXI-MXI-Express Series User Manual
- KnowledgeBase 6GUASNTN: Error Code 10 in Windows Device Manager When Connecting to PXI via MXI